I love a ski road trip! So jealous! Some input from CO:
I'd think about two days at Monarch and a day at CB. There are lots of reasonable CB accommodations in Gunnison 30 mins away. I'll dig up the decent place I stayed at recently for $60/night with breakfast if you want.
Salida is the fantastic little town where you'd stay for Monarch. If you'd be happy for 3 days at Purg, I'd think you'd enjoy Monarch and the typically better surface conditions.
I did the Gunnison to SLC drive in a day then went out that evening. It was easy on a clear day but would have been too much if stormy/icy. If that's the case, I'd suggest driving part of the way Tues afternoon.
I believe your pass also has 3 free days at Copper and Loveland which are sporting some of the better conditions in CO. They both have some decent terrain open and are about open more.
Copper and Loveland are 1.5-2 hours from Salida and don't add much to the drive to SLC. You could head west Tues afternoon after skiing Copper or Loveland and stay in Eagle, Glenwood, Rifle or GJ/Fruita then finish the drive to SLC Wed morning. You might also consider moving from Salida to Leadville Mon night, then you'd be 30 mins from Copper Tues morning.
Here's the most reliable CO snow report that also shows you how much terrain is open by difficulty:
https://www.coloradoski.com/snow-report
In general, I'd delay the decision and go to the best snow wherever that is, CO, UT or WY! The nice thing about the areas you are considering is they all have readily available reasonable last-minute accommodations.